1. Field of the Invention
This invention relates to an artificial heart and, more particularly, a completely implantable artificial heart.
2. Description of the Prior Art
The development of an artificial heart to replace the function of a diseased human heart is an important goal for medical science. The principal deficiencies of the prior art artificial hearts include the bulky size and weight of the devices and the high power required to operate them. A compact, energy efficient artificial heart has the potential of helping thousands of persons with severe heart disease.
At present, there are several types of artificial hearts that are under development. In one design, a hydraulic fluid is pumped to compress a valved blood sac of the left blood pump. The pump then reverses and the hydraulic fluid is directed to compress the sac of the right blood pump. The high speed required by the hydraulic fluid pump, and the rapid reversing, may place excessive forces on the bearings of the pump motor. Moreover, no suitable control system has been developed.
One example of a hydraulic pump for an artificial heart is shown in U.S. Pat. No. 3,048,165, issued to Norton. In the U.S. Pat. No. 3,048,165 , the blood sacs are cyclically contracted and expanded by several magnetically operated diaphragms that force the hydraulic fluid into the chamber containing the sacs. Each diaphragm is attached to a plunger and gear mechanism that meshes with a sun gear so that the movement of one pump causes the other pumps to move. The wear on the numerous moving parts may reduce the reliability of the device.
In a second design, the two valve blood pumps are located on either side of a motor activated system. Pusher plates alternately cause pumping in the left blood pump and then the right blood pump.
A similar system is shown in U.S. Pat. No. 4,310,930 issued to Goldowsky. An oscillating vane alternately forces blood out of the left and right blood chambers Special valves are provided that permit blood to leak back into the right chamber while blood is being pumped out of that chamber. The valve system is an energy inefficient means for compensating for the requirement that the right side of the heart pumps less blood than the left side.
In a third system, two separate and complete motor driven blood pumps are implanted to provide circulation. This system is also bulky, and it is therefore difficult to implant within the chest. Thus, there is a need for a completely implantable artificial heart system that is compact in weight and size for ease in implantation.